Why will my new computer lag when displaying HD video?

My brother and I recently bought a new custom built computer specifically for HD video editng. Here are the specs:

CPU: AMD Phenom Quad Core 940

Motherboard: Asus M4A78

Video Card: EVGA Nvidia Geforce 9500 GT

Ram: 8 Gb 1066 (However, I am running Windows 32 bit so it only shows up as around 2 gbs.)

As you can see, the specs are great. I have more than enough power to play and edit HD video. However, whenever I try to edit or even export and then watch the content, the HD video lags. I am stumped. Why would it lag?

I am using the AVCHD format to edit in, and Sony Vegas Platinum 9 to edit with.

Could you guys help me out? I'd appreciate it. Sorry if this isn't in the right place, I didn't know where it should go!

Well first of all if you have 8Gb of ram using a 32bit OS the PC should see 3.25Gb an not 2GB like you posted. So make sure that is covered before you do anything...

The 9500GT is not going to give you enough frames to view HD 1080p playback, on the other hand 720p should run fine w/o any lag whatsoever. 9500Gt's are known for lagging at 1080p resolutions, specially if it is the 512MB version. 1080p needs more than 32 SP's to run without lagging/stuttering....

My advice would be to try and upgrade to something in the 9600GT/4670 arena and make sure they are 1GB models to give you that extra juice needed for such high resolutions.

Thanks for your help. I really appreciate it. I checked the RAM and it shows up as 3.25 GBs, so that's good. It seems to fluctuate though... I'm positive it was less than that a few weeks ago. But anyway...

You say I'll need a 9600GT to get 1080p playback? I can try to return the model I bought to the store - just bought it this week. I do have the 1 GB model, and I will make sure the new one I buy is a 1 GB model as well.

I was under the impression that the computer I bought would play HD right out of the box... hmm, I will try the new graphics card though. Just a random thought - the 3.25 GBs I have should be enough to play HD video, right? Any other advice?

of course you can get 1080P with cheaper cards but the issue with skimping on the card right now is that you will end up having to upgrade sooner than later so spend as much as you can on the card and this way you save in the longrun...

@OverClkr: Are you sure that the video card is the problem? This is something that I've been wondering about recently. ATI and nVidia claim that even their low-end video cards can play 1080P video, but my system (Athlon 64 with Radeon HD2600) stutters even when playing HD content on YouTube or Vimeo, whereas my sister's MacBook with a Core 2 Duo plays it flawlessly, despite the far inferior Intel integrated graphics. Some new netbooks can reportedly play HD video because of their integrated nVidia graphics.

Well as far as 1080p goes it really stresses the GPU.. I have a netbook as well (ATOM 1.6Ghz) and it cannot do 1080p regardless.....Macbooks use the 8800M GPU's that have 112 Sp's.... That is more than enough for 1080p

Me personally, I have never seen 1080p run at respectable frames with anything under a 9600GT or ATI equivalent. Yes you might get a 9500GT to run 1080p but not with the frames needed to sustain flawless playback.

You have to remember that the 9500GT is considered more than low end, 32 SP's is VERY low specially for the amount of processing power that 1080p requires .... The 8800GT is a much faster GPU and can handle any HD playback but they are hard to find at a good price......

I went to Micro Center today and bought the EVGA GTS 250 (512 Megabytes). The salesman said that for the money, the 250 was slightly better than the 9800, and he also said that 512 megabytes would be more than enough to handle HD video. I installed the card but am seeing no improvement. Any suggestions? This is really starting to frustrate me considering I spent over a thousand dollars total to achieve a complete HD workstation. Thanks for your time.

@OverClkr: Are you sure that the video card is the problem? This is something that I've been wondering about recently. ATI and nVidia claim that even their low-end video cards can play 1080P video, but my system (Athlon 64 with Radeon HD2600) stutters even when playing HD content on YouTube or Vimeo, whereas my sister's MacBook with a Core 2 Duo plays it flawlessly, despite the far inferior Intel integrated graphics. Some new netbooks can reportedly play HD video because of their integrated nVidia graphics.

How does one enable these features?

The 2600 is not really a stellar card, it might handle 720p but I doubt 1080p. Also Flash video currently uses the CPU for rendering, that is why some people are awaiting for the Adobe to release Flash that uses the GPU. That is why your sister's MacBook could play youtube videos, as the Core 2 is leaps ahead of the Athlon64 and not because of the integrated graphics.

When you play avi, mpeg, mp4, etc on a video player that uses hardware acceleration (uses the graphics card, i.e. Windows Media Player, Quicktime, VLC, MPC, etc) then would the graphics card only come to play.

michaelbashaw said:

I went to Micro Center today and bought the EVGA GTS 250 (512 Megabytes). The salesman said that for the money, the 250 was slightly better than the 9800, and he also said that 512 megabytes would be more than enough to handle HD video. I installed the card but am seeing no improvement. Any suggestions? This is really starting to frustrate me considering I spent over a thousand dollars total to achieve a complete HD workstation. Thanks for your time.

Might be the hard drive? It could be the bitrate is so high that your hard drive could barely feed it to the video card. What is your hard disk, and could you try running HDTach and tell us the speed that it is able to determine (or post the graph). Also could you tell us the bitrate of the video (use GSpot or VLC or some other util).

Detailed Benchmark ResultsSpeed at position 0% : 69.57MB/s (78%)Speed at position 3% : 89.11MB/s (100%)Speed at position 7% : 88.13MB/s (99%)Speed at position 10% : 80.46MB/s (90%)Speed at position 13% : 80.45MB/s (90%)Speed at position 17% : 81MB/s (91%)Speed at position 20% : 78.27MB/s (88%)Speed at position 23% : 78.27MB/s (88%)Speed at position 27% : 78.27MB/s (88%)Speed at position 30% : 75.22MB/s (84%)Speed at position 33% : 78.27MB/s (88%)Speed at position 37% : 73.4MB/s (82%)Speed at position 40% : 75MB/s (84%)Speed at position 43% : 72.12MB/s (81%)Speed at position 47% : 71.71MB/s (80%)Speed at position 50% : 71MB/s (80%)Speed at position 53% : 71MB/s (80%)Speed at position 57% : 69.43MB/s (78%)Speed at position 60% : 69.38MB/s (78%)Speed at position 63% : 65.14MB/s (73%)Speed at position 67% : 68.25MB/s (77%)Speed at position 70% : 63.7MB/s (71%)Speed at position 73% : 61.33MB/s (69%)Speed at position 77% : 61.32MB/s (69%)Speed at position 80% : 60.62MB/s (68%)Speed at position 83% : 54.38MB/s (61%)Speed at position 87% : 52.14MB/s (59%)Speed at position 90% : 51.43MB/s (58%)Speed at position 93% : 47.6MB/s (53%)Speed at position 97% : 44.9MB/s (50%)Speed at position 100% : 46.52MB/s (52%)Random Access Time : 13.63msFull Stroke Access Time : 13.28ms

Let me know if you encounter any other issues.... Normally it is something minor when you cannot get flawless HD playback... With your system you should be able to play files that are even higher than 1080p